Muffler and spark arrester

ABSTRACT

A muffler is described with a housing having an input and an output. At least one plate is disposed within the housing to divide it into at least a first and a second internal expansion chamber. At least one tube is disposed through the plate, the tube having first and second ends with a bend therebetween, the bend altering an orientation of the second end of the tube so that the second end faces an interior surface of the housing. The housing, the plate and the tube establish a path for the exhaust between the input and the output. In addition, the first and second internal expansion chambers cooperate to attenuate sound, and the tube assists in sound attenuation and/or affects the path of the exhaust to arrest the discharge of sparks from the output.

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 60/259,702, which was filed on Jan. 5, 2001, the contents of which are incorporated by reference in their entirety.

1. FIELD OF THE INVENTION

[0002] The present invention generally relates to the field of muffler systems for internal combustion engines. More particularly, the present invention relates to a combined muffler and spark arrester for attenuating sound and for reducing or eliminating the discharge of glowing hot carbon particles that typically become entrained in the exhaust gases produced by an engine.

2. DESCRIPTION OF RELATED ART

[0003] The by-products produced by internal combustion engines as a result of burning fossil fuels, such as gasoline, include exhaust gases (typically, water, carbon dioxide, and other gases) and carbon particles. Due to the extreme heat produced during the combustion reaction, the carbon particles that become entrained in the exhaust gases usually are glowing hot and, as a result, are referred to as sparks.

[0004] If these sparks are discharged from the exhaust system, they might initiate a fire, especially if an operator drives the vehicle through a wooded area. As a result, it is not uncommon for designers to incorporate structures in their exhaust systems to delay and substantially prevent the expulsion of sparks until after the carbon particles have cooled sufficiently so that they no longer present a risk of fire. For example, in accordance with USDA Standard 5100, at least 80% of the carbon particles should be maintained within the arrester, with only small non-harmful, particles being released. Structures incorporated into an exhaust system that perform this function are referred to as “spark arresting” because of the function performed.

[0005] As the name suggests, mufflers attenuate the sound of the engine to reduce the ambient noise levels generated thereby. The structures that muffle sound also may function to attenuate sparks discharged by the engine.

[0006] One prior art example is illustrated in FIG. 1. The muffler shown incorporates structures that combine both sound muffling and spark arresting functions.

[0007] As FIG. 1 illustrates, after combustion, exhaust gases and carbon particles (sparks) are discharged by the engine and directed to the muffler 100. After entering the muffler 100 through inlet port 101, the exhaust and sparks pass through a series of expansion chambers 102 a-102 f. The expansion chambers 102 a-102 f cause the exhaust gases to expand and contract repeatedly, thereby attenuating the sound of the engine. One or more pipes 112 (often referred to as “tune pipes”) also are incorporated into muffler 100 to assist in attenuating the sound of the engine.

[0008] Muffler 100 also includes a plate 104 separating expansion chamber 102 c from expansion chamber 102 d. A number of perforations 105 (FIG. 2) pass through plate 104. A plate portion 105 b (shown in detail in FIG. 2) extends at an angle from a point adjacent to each perforation 105. Plate portions 105 b are angled to direct the exhaust stream in a circular direction within exhaust chamber 102 d.

[0009] Additionally, after passing through plate 104, as a result of the centrifugal force established by the circular motion of the exhaust gases, the majority of the carbon particles are thrown against the side walls of exhaust chamber 102 d and become trapped specifically in chamber 102 e of the muffler 100. This reduces or eliminates almost all of the carbon particle sparks directed to the exit of muffler 100.

[0010] Also as illustrated in FIG. 1, muffler 100 includes a tuning chamber 103 that assists in reducing exhaust noise. Tuning chamber 103 typically houses an insulation material, such as glass wool or other similar acoustically absorbent material. The acoustically absorbent material assists in attenuating the sound produced by the engine and also may function to trap the carbon sparks.

[0011] Acoustically absorbent materials, however, are not the only materials that may be positioned along the travel path of the exhaust gases as they travel from the inlet (such as inlet 101) to the discharge end of a muffler. As recognized by those skilled in the art, metal screens may be disposed at intervals in the exhaust travel path to help attenuate sound and trap carbon particles in the mesh. However, such screens may become clogged with carbon particles and create a significant back pressure that may adversely affect the operation of the engine. Therefore, the screen must be removable and checked periodically, e.g., every 100 hours, thereby increasing the manufacturing cost to the manufacturer and maintenance cost to the owner of the machine.

[0012] As made apparent by the drawings, muffler 100 establishes a convoluted travel path through expansion chambers 102 a-102 f. Not only does the convoluted path attenuate sound, it also lengthens the travel time of the carbon particles (sparks) through muffler 100. As a result, muffler 100 both attenuates sound and also reduces or eliminates the discharge of sparks.

[0013] U.S. Pat. No. 5,627,351, issued on May 6, 1997 to Okuma et al. and assigned to Honda Giken Kogyo Kabushiki Kaisha of Japan, describes an alternative approach to the prevention of spark discharge. Okuma et al. discloses a spark arrester that includes a filter structure with a cylindrical body disposed in an expansion chamber of a muffler assembly. Carbon particles (sparks) are filtered from the exhaust stream as the exhaust travels from one chamber in the muffler to another. The cylindrically shaped, metal mesh screen acts as the filter for the carbon particles in this muffler design.

[0014] While the prior art provides several examples of mufflers that effectively attenuate sound and reduce the emission of sparks, they usually rely on a number of exhaust chambers (such as chambers 102 a-102 f illustrated in FIG. 1) to accomplish these functions. The division of a muffler into many separate chambers increases the overall weight of the muffler. In addition, the greater the number of chambers in the muffler, the greater the cost to manufacture that muffler.

[0015] Accordingly, a need has developed for a muffler system with few internal chambers that can attenuate noise and reduce or eliminate the emission of sparks so that the muffler will be both lightweight and more economical to manufacture.

[0016] Finally, a need has developed for more compact (in size) mufflers that perform the functions discussed above. Smaller mufflers save space, thereby providing more room for other components in the host vehicle, such as an automobile or a recreational vehicle.

SUMMARY OF THE INVENTION

[0017] It is, therefore, one aspect of the present to improve the noise attenuation and spark arresting capabilities of mufflers by comparison with those in the prior art.

[0018] Another aspect of the present invention is to reduce the number of chambers within a muffler without sacrificing the muffler's ability to attenuate sound and reduce or eliminate the discharge of sparks.

[0019] Another aspect of the present invention is to provide an All Terrain Vehicle (“ATV”) with a muffler system that minimizes risk of fire to minimize environmental damage caused by the use of ATVs in woodland terrain.

[0020] According to one preferred embodiment of the present invention, a muffler is described with a housing having an input and an output. At least one plate is disposed within the housing to divide it into at least a first and a second internal chamber. At least one tube is disposed through the plate, the tube having first and second ends with a bend therebetween, the bend altering an orientation of the second end of the tube so that the second end faces an interior surface of the housing. The housing, the plate, and the tube establish a path for the exhaust between the input and the output. In addition, the first and second internal chambers cooperate to attenuate sound, and the tube affects the path of the exhaust to arrest the discharge of sparks from the output.

[0021] These and other aspects of the present invention will be revealed by the discussion that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate preferred embodiments of the invention and, together with the description, explain aspects, advantages, and principles of the invention. In the drawings:

[0023]FIG. 1 illustrates a cross-sectional view of a prior art muffler system and its associated muffler chamber;

[0024]FIG. 2 illustrates a cross-sectional view of a perforated plate of the prior art assembly of FIG. 1;

[0025]FIG. 3 illustrates a side view of an exemplary ATV that embodies the present invention;

[0026]FIG. 4 is a schematic view of an exemplary engine muffler system in accordance with the present invention;

[0027]FIG. 5 is a perspective view of a partitioning member and separating tubes in accordance with the present invention;

[0028]FIG. 6 is a side view of one of the separating tubes of FIG. 5; and

[0029]FIG. 7 is a plan view of the partitioning members and the tubes illustrated in FIG. 5.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0030] The following detailed description refers to the accompanying drawings that illustrate exemplary embodiments consistent with the present invention. Other embodiments are possible and modifications may be made to the embodiments without departing from the spirit and scope of this invention. Therefore, the following detailed description is not meant to limit the invention solely to the embodiments described.

[0031]FIG. 3 is a perspective view showing an all-terrain vehicle (ATV) 100. The ATV 100 includes a frame 120 from which a pair of front wheels 102 and a pair of rear wheels 103 are operatively suspended. Handlebars 110 operatively connect to wheels 102 to provide steering for ATV 100. Also, a seat 104 is disposed in frame 120 to accommodate a rider of the ATV 100. A suitable power unit, e.g., an internal combustion engine 150, is carried by frame 120 and provides drive power for (either or both of) the front and rear wheels 102 and 103 through a suitable transmission (not shown). Exhaust from the engine 150 is conducted to a muffler 1 constructed in accordance with the present invention.

[0032]FIG. 4 provides a detailed view of the muffler 1 in which exhaust from the engine 150 enters through an inlet, e.g., inlet port 4. As discussed above, the engine exhaust is hot and may contain sparks that are formed of hot carbon particles. The exhaust is channeled through the inlet port 4 and provided to a first expansion chamber 6. The first expansion chamber 6 is provided as a first stage of noise reduction for the engine exhaust, reducing the noise by alternately compressing and expanding the hot gases in the engine exhaust. The first expansion chamber 6 may be configured to filter noises within a first predetermined frequency range. The first predetermined frequency range could include, for example, low frequency noises. For example, as shown in FIG. 4, the first expansion chamber may include a first screen 7 with a double-walled structure having a first wall 7 a with holes or perforations and a second wall that is substantially solid. A sound absorbing material, e.g., stainless steel wool, may be provided between the first and second walls 7 a and 7 b for alternating sound.

[0033] A first end of the first expansion chamber 6 is connected with the inlet port 4 and configured to receive the exhaust from the inlet port 4. The other end of the first expansion chamber 6 is connected with a first end of a cylindrical housing 8. As shown in FIG. 4, the first expansion chamber 6 forms a partial coaxial connection with the cylindrical housing 8.

[0034] Next, a disc-shaped partitioning member 10 is provided for partitioning the cylindrical housing 8 into a first portion 8 a and a carbon accumulation section 8 b. The partitioning member 10 may be connected to the housing 8, e.g., by welding. The first portion 8 a defines a second expansion chamber. The partitioning member 10 includes a number of apertures 11 for placement of a corresponding number of tubular pipes 12 therethrough. FIG. 5 provides a more detailed view of the partitioning member 10, the apertures 11, and the tubular pipes 12.

[0035] In FIG. 5, the apertures 11 are shown to be positioned near a peripheral edge of the partitioning member 10. Each pipe 12 has a proximal end 12 a and a distal end 12 b portion, as illustrated more clearly in FIG. 6. Additionally, when placed within the cylindrical housing 8, each pipe 12 is positioned such that its proximal end 12 a is positioned between the partitioning member 10 and the first expansion chamber 6. Further, as illustrated in FIG. 6, each pipe 12 is straight at its proximal end 12 a and has a bend 12 c at its distal end 12 b. Further, as illustrated in FIG. 4, a longitudinal axis 12′ of the pipes 12 is shown to be aligned with a longitudinal axis 9 of the cylindrical housing 8, although the axis 12′ could be angled with respect to the axis 9.

[0036] The positioning of the partitioning member 10 within the cylindrical housing 8, and the insertion of the tubular pipes 12 through the apertures 11 of the partitioning member 10, facilitate the separation of the carbon particles from the exhaust gases. During operation, the hot gases of the engine exhaust flow through the first expansion chamber 6 and into the second expansion chamber 8 a. While the gases flow completely through the tubular pipes 12 and through the carbon accumulation section 8 b of the cylindrical housing 8, the carbon particles are extracted from the exhaust gas at least in part by the tubular pipes 12 and are then trapped in the carbon accumulation section 8 b. Specifically the bends 12 c (FIG. 6) in the distal end portions 12 b of the pipes 12 direct the carbon particles into a carbon trap 14 of the carbon accumulation section 8 b. The carbon trap 14 could include a screen 20.

[0037] The length of the pipes 12, the angle of the bends 12 c, and the precise angular orientation of the distal end portions 12 b are determined based upon the degree of desired carbon particle arresting and other desired performance characteristics of the muffler system 1, such as frequency attenuation. For example, the length, the angle of the bends and/or other dimensions (e.g., the diameter) of the pipes 12 can be selected to attenuate sound at a predetermined frequency. Similarly, a diameter and/or cross-section of the tubes 12 also is chosen based upon desired operational characteristics.

[0038]FIGS. 6 and 7 illustrate angles associated with the pipes 12. FIG. 6 shows an angle (α) associated with each pipes 12 and formed by the intersection of the axis 12′ and an axis 12″. Each angle (α) may be within a range of angles, e.g., from 5 to 90 degrees, depending on desired muffler characteristics. Of course, the angle (α) could be more than 90° or less than 5°, if desired. Angle (α), shown in FIG. 7, is formed from an intersection of an axis 10′ or an axis 10″ of the partitioning member 10, with the axis 12″ of one of the pipes 12. The angle (α) may be within a range of angles from 0 to 90 degrees, depending on the desired muffler characteristics. Of course, the angle (β) could be less than 0° or greater than 9° if desired. In the example shown, the angle (β) is 65°, the angle y is 85°, and the angle Ø is 55°.

[0039] The bends 12 c are structured and arranged to channel the carbon particles in the direction of the carbon trap 14. A combination of factors, such as the velocity of the carbon particles, their direction of travel, and gravity, cause the particles to accumulate in the carbon trap 14. The carbon particles enter the tubular pipes 12 at the proximal end 12 a and flow through the pipe 12. The movement of the exhaust causes the particles to exit the pipes through the distal end 12 b. Since the distal ends 12 b are angled, the particles exit the tubes 12 and enter the carbon trap 14 in a rotating manner, creating centrifugal motion. The centrifugal motion of these rotating particles causes the particles to accumulate along the inside of the carbon trap 14. Although the apertures 11 in the positioning member 10 are shown to be symmetrically arranged with respect to one another, this symmetrical arrangement is not required.

[0040] Since the carbon particles from the engine exhaust become trapped in the carbon trap 14, over time these trapped particles begin to accumulate. In order to remove these accumulated particles, a plug 16 is provided. A user of the muffler system 1 can remove the plug 16 in order to release the accumulated carbon particles from the carbon accumulation section 8 b.

[0041] Next, a noise absorption section 18 is provided in the carbon accumulation section 8 b for reducing the noise associated with the engine exhaust gases. Finally, an outlet port 26 is provided adjacent to the noise absorption section 18 to permit the engine exhaust gases to escape into the atmosphere. A second screen 24, which may be similar in construction to the first screen 7, is provided in an outlet of the muffler 1, e.g., a port 26, to provide filtering of noises within a second predetermined frequency range. The second screen 24 could be filled with, for example, stainless steel wool. The second frequency range may include, for example, higher frequency noises.

[0042] As seen in the illustration of FIG. 4 and the discussion above, the carbon particle arresting function and the tuning function are performed in only a few chambers, unlike prior art systems that require many chambers to perform the separation and tuning functions. Therefore, a muffler system constructed and arranged in accordance with the present invention can be manufactured more easily and provided in a smaller muffler housing. Also, a muffler system in accordance with the present invention is capable of performing the same functions as conventional muffler systems in larger housings.

[0043] The foregoing description of the preferred embodiments provides an illustration and description, but is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible consistent with the above teachings or may be acquired from practice of the invention. 

What is claimed is:
 1. A muffler, comprising: a housing having an input and an output, the input adapted to receive exhaust from an internal combustion engine that includes at least one of exhaust gases and sparks; at least one plate disposed within the housing, dividing the housing into at least a first and a second internal chamber; and at least one tube disposed through the plate, the tube having first and second ends with a bend therebetween, the bend altering an orientation of the second end of the tube so that the second end faces an interior surface of the housing, wherein the housing, the plate, and the tube establish a path for the exhaust between the input and the output, wherein the first and second internal chambers cooperate to attenuate sound, wherein the tube affects the path of the exhaust to arrest the discharge of sparks from the output.
 2. The muffler of claim 1, wherein the tube has a length and a diameter selected to attenuate sound at a predetermined frequency.
 3. The muffler of claim 1, further comprising a second plate disposed within the second internal chamber to establish a spark trap within the second internal chamber.
 4. The muffler of claim 3, further comprising a plug disposed through the side wall of the housing within the spark trap to permit the removal of carbon particles from the spark trap after a predetermined period muffler operation.
 5. The muffler of claim 1, wherein the at least one tube comprises three tubes.
 6. The muffler of claim 5, wherein the three tubes are arranged generally in the shape of a triangle.
 7. The muffler of claim 5, wherein each of the tubes includes a first segment between the first end and the bend with a first axis substantially aligned with a longitudinal axis of housing.
 8. The muffler of claim 7, wherein each of the three tubes includes a second segment between the bend and the second end that define a second axis disposed at a first predetermined angle to the first axis of the first segment.
 9. The muffler of claim 8, wherein the first predetermined angle is between about 5 and 90 degrees.
 10. The muffler of claim 9, wherein the at least one plate defines a plate axis parallel thereto, and wherein the second axis is disposed to the plate axis at a second predetermined angle.
 11. The muffler of claim 10, wherein the second predetermined angle is between about 0 and 90 degrees.
 12. The muffler of claim 8, wherein the first predetermined angle is substantially the same for each of the three tubes.
 13. The muffler of claim 1, wherein the at least one plate is disposed a predetermined distance away from the input of the housing.
 14. The muffler of claim 1, further comprising a first screen disposed within or adjacent the inlet at least to muffle a first sound type within a first predetermined frequency range.
 15. The muffler of claim 14, wherein the inlet is a tubular member with the first type screen disposed therein.
 16. The muffler of claim 14, further comprising a second screen disposed within or adjacent the outlet at least to muffle a second predetermined frequency range.
 17. The muffler of claim 16, wherein the outlet is a tubular member, and the second screen is positioned within the outlet.
 18. An all terrain vehicle, comprising: a frame; front and rear wheels suspended from the frame; an engine including an exhaust outlet mounted on the frame; and a muffler comprising: a housing having an input and an output, the input adapted to receive exhaust from an internal combustion engine that includes at least one of exhaust gases and sparks; at least one plate disposed within the housing, dividing the housing into at least a first and a second internal chamber; and at least one tube disposed through the plate, the tube having first and second ends with a bend therebetween, the bend altering an orientation of the second end of the tube so that the second end faces an interior surface of the housing, wherein the housing, the plate, and the tube establish a path for the exhaust between the input and the output, wherein the first and second internal chambers cooperate to attenuate sound, wherein the tube affects the path of the exhaust to arrest the discharge of sparks from the output.
 19. The all terrain vehicle of claim 18, wherein the tube has a length and a diameter selected to attenuate sound at a predetermined frequency.
 20. The all terrain vehicle of claim 18, wherein the muffler further comprises a second plate disposed within the second internal chamber to establish a spark trap within the second internal chamber.
 21. The all terrain vehicle of claim 20, wherein the muffler further comprises a plug disposed through the side wall of the housing within the spark trap to permit the removal of carbon particles from the spark trap after a predetermined period muffler operation.
 22. The all terrain vehicle of claim 18, wherein the at least one tube comprises three tubes.
 23. The all terrain vehicle of claim 22, wherein the three tubes are equidistantly spaced generally in the shape of a triangle.
 24. The all terrain vehicle of claim 22, wherein each of the three tubes includes a first segment between the first end and the bend with a first axis substantially aligned with a longitudinal axis of housing.
 25. The all terrain vehicle of claim 22, wherein end of the three tubes includes a second segment between the bend and the second end that define a second axis disposed at a first predetermined angle to the first axis of the first segment.
 26. The all terrain vehicle of claim 25, wherein the first predetermined angle is between about 5 and 90 degrees.
 27. The all terrain vehicle of claim 25, wherein the at least one plate defines a plate axis parallel thereto, and wherein the second axis is disposed to the plate axis at a second predetermined angle.
 28. The all terrain vehicle of claim 27, wherein the second predetermined angle is between about 0 and 90 degrees.
 29. The all terrain vehicle of claim 25, wherein the first predetermined angle is substantially the same for each of the three tubes.
 30. The all terrain vehicle of claim 18, wherein the at least one plate is disposed a predetermined distance away from the input of the housing.
 31. The all terrain vehicle of claim 18, further comprising a first screen disposed within or adjacent the inlet at least to muffle a first sound type within a first predetermined frequency range.
 32. The all terrain vehicle of claim 31, wherein the inlet is a tubular member with the first type screen disposed therein.
 33. The all terrain vehicle of claim 31, further comprising a second screen disposed within or adjacent the outlet at least to muffle second predetermined frequency range.
 34. The all terrain vehicle of claim 33, wherein the outlet is tubular and the second screen is positioned within the outlet.
 35. A muffler, comprising: a housing having an input and an output, the input adapted to receive exhaust from an internal combustion engine that includes at least one of exhaust gases and sparks; at least one plate disposed within the housing, dividing the housing into at least a first and a second internal chamber; and at least one tube disposed through the plate, the tube having first and second ends with a bend therebetween, the bend altering an orientation of the second end of the tube so that the second end faces an interior surface of the housing, wherein the tube is dimensioned to attenuate sound at a predetermined frequency and affects the path of the exhaust to arrest the discharge of sparks from the output.
 36. An all terrain vehicle, comprising: a frame; front and rear wheels suspended from the frame; an engine including an exhaust outlet mounted on the frame; and a muffler comprising: a housing having an input and an output, the input adapted to receive exhaust from an internal combustion engine that includes at least one of exhaust gases and sparks; at least one plate disposed within the housing, dividing the housing into at least a first and a second internal chamber; and at least one tube disposed through the plate, the tube having first and second ends with a bend therebetween, the bend altering an orientation of the second end of the tube so that the second end faces an interior surface of the housing, wherein the tube is dimensioned to attenuate sound at a predetermined frequency and affects the path of the exhaust to arrest the discharge of sparks from the output. 